摘要:为了阐明极度退化的崩岗生态系统内芒萁的生长状态和养分储存特征，对闽西南3处不同侵蚀强度的典型崩岗内芒萁叶片C、N、P含量及C/N、C/P、N/P特征进行研究，对比分析不同侵蚀强度下崩壁部位和崩岗不同侵蚀部位中芒萁叶片的生态化学计量特征。结果表明：崩岗内芒萁叶片的C、N、P平均含量分别为477.10 g·kg-1、6.45 g·kg-1、0.25 g·kg-1，芒萁叶片的N、P养分含量极低；而C/N、C/P、N/P平均值分别为96.82、2 097.20、27.67，芒萁生长受P限制。不同侵蚀强度下的崩壁内芒萁叶片的C、N、P含量及C/P、N/P均存在显著差异（P < 0.05），C含量、C/P和N/P均随着侵蚀强度的增强而减小，N含量在中度侵蚀的崩壁内较高，而P含量则随着侵蚀强度的增强而增加，表明芒萁对土壤侵蚀严重的崩岗生态系统具有很强的适应能力。在崩岗的不同侵蚀部位中芒萁叶片的P含量、C/P和N/P均存在显著差异（P < 0.05），P含量在集水坡面最高，在崩壁最低；而C/P、N/P均表现为崩壁显著大于其他各侵蚀部位。可见，在崩岗的不同侵蚀部位，崩壁中芒萁对C的同化能力强于其他侵蚀部位，且对P利用效率也显著高于其他侵蚀部位。综上，在侵蚀严重的崩岗生态系统中，芒萁有较强的同化C能力和较高的对P利用效率，能通过调节自身C、N、P元素含量很好地适应土壤侵蚀严重、养分极度贫瘠的生境。
关键词:生态化学计量学/
芒萁叶片/
崩岗/
土壤侵蚀强度/
侵蚀部位
Abstract:Collapse mound is a form of widespread and severe soil erosion in granite areas in South China. As a typical pioneer plant in collapse mound areas, Dicranopreris dichotoma is critical for soil and water conservation in collapsing erosion areas in South China. Plant stoichiometric characteristics reflect the capacity of plants to absorb and store mineral nutrients from the soil. They also reflect the long-term stoichiometric distribution formed during plant adaptation to the environment. Therefore, analysis of the characteristics of ecological stoichiometry of D. dichotoma in collapsing erosion areas can provide an important guidance for ecological restoration in collapsing erosion areas. In order to clarify the characteristics of nutrient storage of D. dichotoma in extremely degraded collapse mound ecosystems, the characteristics of carbon (C), nitrogen (N), phosphorus (P) contents and C/N, C/P and N/P ratios for D. dichotoma leaf in three typical collapse mound areas with different erosion intensities in Southwest Fujian Province were analyzed. The ecological stoichiometry characteristics of D. dichotoma leaves in different erosion intensities of collapsing wall and collapse mound under the same erosion intensity in different erosion positions were also comparatively analyzed. The results showed that the average contents of C, N and P in the leaves of D. dichotoma in collapse mounds were 477.10 g·kg-1, 6.45 g·kg-1 and 0.25 g·kg-1, respectively. The N and P contents were generally extremely low. The average ratios of C/N, C/P and N/P were 96.82, 2 097.20 and 27.67, respectively. Thus D. dichotoma growth was primary limited by P content. On the other hand, there were significant differences in C, N and P contents, and C/P and N/P ratios in collapsing wall leaves under different erosion intensities (P < 0.05). All the C content along with C/P and N/P ratios decreased with increasing erosion intensity. While N content was higher in collapsing walls with moderate erosion, P content increased with increasing erosion intensity. This showed that D. dichotoma had strong ability to adapt to collapse mound ecosystems with severe soil erosion. On the other hand, there were significant differences in P content, and C/P and N/P ratios in D. dichotom a leaves in different erosion positions of collapse mounds under the same erosion intensity (P < 0.05). P content was highest in the upper catchment and lowest on collapsing walls. All the C/P and N/P ratios on collapsing walls were significantly larger than in other erosion positions. Obviously, it was evident that the ability of D. dichotom a to assimilate carbon in collapsing walls was stronger than in other erosion positions of collapse mounds. In addition, P utilization efficiency in collapsing walls was significantly higher than that in other erosion positions. In conclusion, D. dichotom a had strong ability to assimilate C and use P efficiently in severely eroded gully ecosystems and was adaptive to environments with severe soil erosion and extreme nutrient deficiency by regulating C, N and P contents in its cells.
Key words:Ecological stoichiometry/
Dicranopreris dichotoma leaf/
Collapse mound/
Soil erosion intensity/
Erosion position
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